Recommended replacement Bottom Bracket....

by Dangermouse   June 24, 2014  

Hi all

I'm currently riding a Spesh Tricross that has a BB-7420 bottom bracket with crank bolts but it's nearing the end of it's life!
It's been suggested to me that it's a pretty pants bottom bracket anyway so wondered if any of you could recommend a better replacement please?
It's also got an FSA Temp triple crankset fitted but I'm happy to listen to suggestions for replacing that too!

Thanks Wink

4 user comments

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The BB-7420 came in different spindle lengths. The length should be printed on it, but it's probably only visible if you remove it from the bike.

You should get a bottom bracket of the exact same dimensions as the one you are removing, and you should have quite a few choices ranging from cheap to high quality.

If you are considering replacing the crankset then you should definitely make that decision before replacing the bottom bracket, since any investment in the bottom bracket will be wasted if you replace the crankset.

posted by Derny [35 posts]
24th June 2014 - 6:33

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That's an easy one, well it is for me having done exactly that replacement this spring. That FSA part is a little notorious for conking out early, so I swapped my own after riding it through the Winter rather than wait for it to happen.

Buy yourself a Shimano UN55, cheap (under £15 online), reliable and very easy to find.

For Specialized, you'll probably be able to find size details for the BB online somewhere, otherwise as Derny says, pull the old one out. If you can't get the exact width, you have a little wiggle room. I had to replace a 103mm with a 107mm as that's the smallest size for the UN55, but still within reach of the front mech after adjustment.

posted by bikebot [452 posts]
24th June 2014 - 7:21

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bikebot wrote:
That's an easy one, well it is for me having done exactly that replacement this spring. That FSA part is a little notorious for conking out early, so I swapped my own after riding it through the Winter rather than wait for it to happen.

Buy yourself a Shimano UN55, cheap (under £15 online), reliable and very easy to find.

For Specialized, you'll probably be able to find size details for the BB online somewhere, otherwise as Derny says, pull the old one out. If you can't get the exact width, you have a little wiggle room. I had to replace a 103mm with a 107mm as that's the smallest size for the UN55, but still within reach of the front mech after adjustment.

Thanks - the UN55 is a good price! Did you change your crankset too?

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posted by Dangermouse [14 posts]
24th June 2014 - 10:59

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Dangermouse wrote:

Thanks - the UN55 is a good price! Did you change your crankset too?

No, a lot of people advise that for taper mount, but I take it with the same pinch of salt as the advice that you change your cassette with your chain. If you dare to raise the question of whether to grease or not to grease the taper assembly, you'll find a wide range of opinions!

Clean everything up before putting the old chainset back on and use a torque wrench (reversible for the BB) unless you've got a good feel for that much force.

posted by bikebot [452 posts]
24th June 2014 - 11:29

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